Electric control box



L. S. THOMAS ELECTRIC CONTROL BOX July 26, 1960 2 Sheets-Sheet 1 Filed Oct. 24, 1958 L. S. THOMAS ELECTRIC CONTROL BOX July 26, 1960 2 Sheets-Sheet 2 Filed Oct. 24, 1958 INVENTOR. 230,5 51/2? fia/was' flrralfiy United States Patentf) ELECTRIC CONTROL BOX LeslieS; Thomas, Orchard Lake, Mich., assignor to Gem eralMotcrs Corporation, -Detroit,.Mich., a corporation of Delaware Filed on. 24; 1958, SnNo; 769,384

3 Claims. (Cl; 200-50) therefrom. In order to compensate "for these dangers, it'

has been the practice in the past topro'vide some sort of switch actuating mechanism which is directly connected to" the" door latch mechanism such that the switch is automatically shut ofi' when thedooris opened. This type ofcontr'ol'box, however, gives a great 'amount of" difliculty when maintenance on-the switchmeans, or other electrical equipment withinthebox, becomes necessary. Slcille'dmaintenance personnel, in order'to'repair the contents of the box, must be able "toactua'te the'switch when thedooris-open. If theswitch control'is interlocked'to the door actuatingimechanism' for the safety of unauthor ized personnel it may'beseen that maintenance onthe equipment-may be made only "when'the' door is' op'en and 'the switch inthe open or 'olf position."

The other possibility, in order to compensate 'fo'r this disadvantage; is to have'a switch*actuatingzmechanism that 'is in'no way connected or controlled' by:th'e door latch mechanism. Thispossibility, however; is poor from a safety. standpoint; due to the inherent dangersof the switch-beingiclos'ed when'the door is-in an=op'en=position.

The device in which this invention is" embodied corn prises threeinterconriectd mechanisms, a main 'door latch mechanism, a switch actuating mechanism, and a connectingmechanism-between thedoor latch andswitch actuation'.-- With'this-control box it ispossible to actuate the switchmechanism by thedoor' latch structure whereby closing the door'willrequire asecondoperation to actuate theswitch. However,- the door normally may be opened unless the switch is first opened, that is, in the oif'position;

In order'for maintenance personnel to enter the box while theswitch is in a closed positionfa defeater mechanism is provided which disconnects the connecting mechanism from the switch actuating mechanism to allow the maintenance operator to open the-door without opening the switch.--- The'defeater mechanism'isso arranged that'inexperienced or unauthorized personnel could no'topen the box without a special tool, and thus-would be protected from unauthorized entry.

Thus, a control box is provided having numerous safety features, the main feature being the possibility of skilled personnel entering-the box forproper-maintenancepurposes and at the same time eliminating thedangersinherent in-unauthorized personnel entering the control box. The-device is relatively simple to-operate and inexpensive to manufacture. Existing control boxes couldibe-"modified according .to the invention without exorbitant cost, .thus

2 making an industry wide safety feature availableto most all installations.

In the drawings:

Figure'l is an'isometric'view ofthe'control'box embodying thisinvention withthe door shown in an open position'to illustrate thelocation andrelationship of the various parts.

Figure 2 is an elevational view of the control box with the door in phantom and the actuating mechanisms shown in'fulllines to illustrate the'location and'relationship of thepa'rts when'the door is in a closed position.

Figure 3 is a sectional view of a portion of the controlbox shown in Figure 2, taken substantially along the line 3 3 and looking in the direction of the arrows.

Figure4 is a sectional view of a portion of the control box shown in Figure 2, taken substantially along the line 4-'4 and looking in the direction of the arrows.

Figure'S is a sectional view of a portion of the control box shown in' Figure 2, taken substantially along, the line 55 and looking in the direction of the arrows.

Referring'more particularly to the drawings, Figures 1 and 2-best show the over all control box and interconnected linkages. The control box itself comprises top and bottom panels 10and12, side panels 14 and 16, and aback panel 18. A flanged rim 20 extends around'the periphery of the open side of the box to provide a'dirt seal and tarnper proof closure surface for the door 22. The door may be hinged to either of the side panels 14or 16 many suitable manner, such as by a piano type hinge or aplurality of strap or butt hinges. The door 22"'has a flange 24 surrounding the periphery and facing inwardlyto overlie the flange 20 formed on the control box.

A switch 26is mounted in the box, preferably adjacent the corner formed by the side plate 14 and the top plate 10, and'serves to control any type of electrical system, not shown, which'may-be located in the lower portion of the box. A'switch handle 28, rotatably secured in the switch "26 and pivoted on'the shaft 30, actuates the switch 26 toopen or close the usual contacts. 7

The main door latch mechanism is operated by a handle 32'disp'osed'on' the outer surface of the door 22. A shaft 34 extends through the door panel 22, through a spacer member 36, and supportsthe lower latch cam 38." The latch 'cam is providedwith a knife edge 40, and it may be seen'fror'n viewing Figures 1 and'2 that rotation of the handle 32"will'rotate'thelatchcahr'SS to carry the knife edge 40 behindthe'flangedportion 26 of the control box when the'door'is closed. The lower latch cam 38 is secured-forrotation withthe shaft 34 by the set screw 42.

An upper cam 44 of the same configuration as the lower cam 38 is rotatablysecured to the innerside of the door panel 22 by the fiangedspacer member 46 and the shaft 48. The'upper latch cam 44 may be secured to the shaft 48 in any convenient manner as by a Washer 56 held in place by aconventional cotter-pin 52.

A connecting rod 54 is pivotally secured to the upper and lower cams as at 56 and 58 and serves to rotate the upper and lower latch-cams in unison. Rotation of the handle 32 and the lower latch cam 38 will lift the connecting rod 54, which rotates the upper cam 44. A compression spring 60, acting between a tab 62 secured to the connecting rod 54 and a tab 64 secured to the inn; surface of the door panel' 22, biases the connecting rod, and consequently the latch cams, in the lower or opening position, the position shown in Figure 1.-

The switch actuating mechanisrn includes a-platefi havingthe apertures 68 and 70"for-medthe1'ein; A bracket member72', or'a plurality thereof, extends from the plate 66 inwardly of *the box and "is pivoted from the back panel 18 as=by thepivot'sh aft 74. The'bracket 68 in the plate 66 and movement of the plate about the pivot point 74 will open or close the switch 26.

A pair of bearings 76 are secured to the inner surface of the door panel 22, as by bolts 78, and are vertically spaced thereon. A switch actuating rod 80 is vertically movable in the bearings 76 and has attached thereto the hinged switch actuating links 82 and 84, pivotally connected as by the pin'86. The link member 84 extends through the aperture 70 in the plate 66 and it may be seen that vertical movement of the rod 80 will rotate the plate 66 through the links 82 and 84 to actuate the switch handle 28;

A tab 88, having a slot 90 formed therein, is secured to the upper portion of the connecting rod 80 and provides the actuator means for connecting rod. A switch actuating handle 92, located on the outer surface of the door panel 22, extends through an opening 94 in the panel and is secured to the rotating bracket plate 96 by the bolts 98. Rotation of the handle 92 will rotate the bracket plate 96 inside the door panel 22. A pin 100 is secured in the rotating bracket plate 96 and extends into the slot 90 in the tab 88. It is obvious that rotation of the handle 92 will thus actuate the rod 80, the links 82 and 84 and the plate 66 to open or close the usual contacts in the switch 26.

The defeater mechanism is actuated by a pin 102 which extends through the door panel 22 and through a bearing 104. The pin 102 is secured in a plate 106 adjacent the inner surface of the door 22, the connection being such that rotation of the pin 102 will rotate the plate 106. The pin 102 is illustrated as having a slot in the outer end, allowing the pin 102 and the plate 106 to be turned by a conventional screwdriver. However, to prevent unauthorized personnel from operating the mechanism, the pin 102 may have some special configuration in the end to permit operation only by a special tool. A tab 108 secured to the door panel 22 and a compression spring 110 abutting the plate 106, resiliently biases the plate 106 in the position shown in Figures 1 and 2. The purpose of a push bar 112 rigidly secured to the plate 106 and the notch 114 formed in the plate will be later described. Preliminary latching means are provided for the door 22 by a hook member 116, secured to the plate 106, and the preliminary latch bar 118, secured in any convenient manner in the control box. The hook member 116 has a shoulder 120 formed thereon and an inclined surface 122 between the end of the hook member and the shoulder 120. A complementary inclined surface 124 is provided on the end of the preliminary latch member 118. It may be seen that by closing the door 22 the surfaces 122 and 124 will allow the hook member to slide past the end of the preliminary latch member 118, and the shoulder 120 to engage the end of the latch member 118. Thus, the door is retained in a partially closed position, the opening being such that there is no danger to personnel operating the box. The switch actuator'mechanism may then be operated to close the switch 26.

Secured to the connecting rod 54 of the main door latch mechanism is a link 126 which extends toward the center of the door. An arcuate cam surface 128 is formed in the end of the member 126. 130 is pivotally secured to the first link member 126 by a pivot pin 132. The joining surface of the link 130 is complementary to the cam surface 128 of the first link member 126, the member 130 having a stop shoulder 134 adapted to abut the edge of the first link member 126 such that rotation past the shoulder is not possible. The links are biased into the position shown by the torsion spring 136 acting on the'buttons 138. The position just described is as illustrated in Figures 1 and 2. a a

A second link The pivot pin 132 connecting the links 126 and 130, has an extension 140, best seen in Figure 3, extending through the link members 126 and 128 and is adapted to be received in the notch 114 formed in the plate 106.

A stop tab 142 is secured to the switch actuating rod and cooperates with the tip, 144 of the link member 130. The purpose of the abutment will be later described.

The operation of the control box is as follows: With the door 22 open, the parts are in the position shown in Figure 1. When it is desired to close the door and actuate the switch 26, the operator swings the door until the preliminary latch hook 116 engages the latch bar 118. The latch handle =32 is then rotated to engage the latch cams 38 and 44 with the edge 22 of the control box. As the latch cam 38 is rotated and connecting rod 54 raised, the links 126 and 130 also move vertically upwardly with the connecting rod 54 and the extension 140 of the pin 132 engages the inclined surface 146 of the plate member 106. The plate member 106 rotates against the pressure of the spring 110, releasing the preliminary latch means and allowing the door to be fully closed. The extension 140 is received in the notch 114 in the plate 106 and the spring returns the plate 106 to its normal position. The parts are then as shown in full lines in Figure 2.

The switch actuating handle 92 may then be turned from outside the box to close the switch 26, rotation of the handle 92 rotating the bracket plate 96 and raising the switch actuating rod 80, through the tab 88. The pivoted links 82 and 84, extending through the aperture 70 in the plate 66, rotate the plate 66 about the pivot point 74 to actuate the switch handle 28 and close the switch 26. At this time the stop tab 142 on the switch actuating rod 80 is raised into abutment with the end 144 of the connecting link 130. The parts are then as shown in dashed and dotted lines in Figure 2.

The control box is thus operational, the door being closed and the switch 26 actuated, and the box may remain as such for as long as necessary.

When it is desired that the control box he opened the handle 92 is rotated to rotate the plate 66 and the switch handle 28 to open the switch 26. The stop tab 142 drops with the connecting rod 80 and out of the way of the link 130. A screw driver, or other convenient tool, is used to rotate the defeater pin 102, thus rotating the plate 106 and freeing the extension 140 of the pin 132 from the notch 114 of the plate 106. The handle 32 is forcibly rotated by spring 60 to disengage the latch cams 38 and 44 from the side flange 20, allowing the door to be opened.

Ifthe operator should wish to open the door without opening the switch 26 he may do so by leaving the switch actuating handle 92 in the switch-on position and rotating the pin 102 and the defeater plate 106. The push bar 112 rotates the connecting link member out of engagement with the stop tab 142 and at the same time frees the extension of the pin 132 from the notch 114. The door actuator handle 132 is forcibly rotated by spring 60 to free the latch connections 38 and 44 from the side flange. The operator then has access to the-box with the switch in the closed position.

v If the door has not been latched when the switch 26 is actuated, tab 142 on the rod 80 will engage the shoulder 144 on the ring member 130, thus raising the ring members 130 and 126, lifting the latch mechanism and securing the latch cams 38 and 48 behind the flange 20 of the box.

Thus it may be seen that a control box is provided which allows access thereto only by a skilled operator, and preventing entrance by unauthorized personnel. The control box door may be opened with the switch either 1n the on or ofi position at the desire of the operator, it being assumed that the person opening the door is skilled enough to know whether or not the switch should be on or ofi.

I claim:

1. An electric control box comprising a plurality of panels defining an open sided box, a switch secured in said box, a door hingedly secured at one edge to one of said panels, a latch handle rotatably secured to the outside of said door and having a shaft extending through said door, a first latch cam secured to said shaft and rotatable with said handle, a second latch cam rotatably secured to said door and spaced from said first latch cam, a connecting rod pivotally secured to said first and second latch cams to rotate said second cam in conjunction with said first cam when said first cam is rotated by said handle and secure said door to said box in a closed position, switch actuating means secured to said door and vertically movable with respect thereto, means pivotally secured to said switch and within said box and engaged by said switch actuating means to open and close said switch when rotated by said switch actuating means, connecting means operable between said switch actuating means and said connecting rod to actuate said switch actuating means and open said switch when said connecting rod and said latch cams are disengaged from said box to open said door, and independently operated defeater means to disengage said connecting means and actuate said connecting rod and said latch cams to open said door without actuating said switch actuating means and to allow access to said switch and said box when said switch is in a closed position.

2. An electric control box comprising a plurality of panels defining an open sided box, a switch secured to a portion of said panels and within said box defined thereby, and having a switch handle extending therefrom, a door hingedly secured at one edge to one of said panels, latch means rotatably secured to said door and engaging another of said panels to retain said door in a closed position, a bar pivotally secured to said switch within said box and having spaced apertures therein, one of said apertures engaging said switch handle for actuation thereof, a rod secured to said door and vertically movable with respect thereto, link means secured to said rod and movable therewith and extending through another of said apertures to raise and lower said bar and said switch handle to actuate said switch, connecting means operable between said latch means and said rod to move said rod and said bar and said switch handle and open said switch when said latch means are operated to open said door, and independently operated defeater means engaging said connecting means to disengage said connecting means and actuate said latch means for opening said door without actuating said switch and allow access to said switch and said box when said switch is closed.

3. An electric control box comprising a plurality of panels defining an open sided box, a switch secured to a portion of said panels and within said box, a door hingedly secured at one edge thereof to one of said panels, latch means rotatably secured to said door and engaging another of said panels to secure said door in a closed position, switch actuating means secured to said door and vertically movable with respect thereto, means pivotally secured to said switch and within said box and engaged by said switch actuating means to open and close said switch when rotated by said switch actuating means, a connecting link operable between said switch actuating means and said latch means to actuate said switch actuating means and open said switch when said latch means are operated to open said door, a defeater plate pivotaily secured to said door and having a notch formed therein to retain said latch means in a closed position, said defeater plate being rotatable to release said latch means and allow said latch means to disengage from said box for opening of said door, and a push bar secured to said defeater plate and rotatable therewith to disengage said connecting link from said switch actuating means when I said plate is rotated to disengage said latch means and prevent said connecting link from actuating said switch actuating means and opening said switch when said latch means disengages from said box and said door is opened.

References Cited in the file of this patent UNITED STATES PATENTS 2,695,934 Wills Nov. 30, 1954 2,806,099 Rexroad Sept. 10, 1957 2,882,359 Edmunds et al Apr. 14, 1959 

